Target namespace Introduction DualAlongReferent DualAlongReferentPropertyType

44 Copyright © 2012 Open Geospatial Consortium

9.4 Linear Referencing Towards Referent

9.4.1 Target namespace

All schema components specified in this subclause are in the target namespace: http:www.opengis.netgml3.3lrtr

9.4.2 Introduction

Linear Referencing Towards Referent includes the specification of linearly referenced locations which can have a towards referent in their distance expressions.

9.4.3 DualAlongReferent

complexType name=DualAlongReferentType complexContent extension base=gmllr:AlongReferentType sequence element name=towardsReferent type=gmllr:ReferentPropertyType minOccurs=0 sequence extension complexContent complexType element name=DualAlongReferent type=gmllrtr:DualAlongReferentType substitutionGroup=gmllr:AlongReferent gmllrtr:DualAlongReferent implements ISO 19148 LRTR_DualAlongReferent see ISODIS 19148, 6.3.3. For Linear Referencing Methods having a gmllrtr:type of relative, the gmllrtr:DualAlongReferent specifies an optional towards referent. The optional element gmllrtr:towardsReferent specifies a second location along the gmllr:LinearElement to help disambiguate the gmllr:fromReferent and the direction in which the measurement is made. The gmllrtr:towardsReferent overrides the directional sense of the gmllr:LinearElement, and may influence the offset direction if an offset is included. When a gmllrtr:towardsReferent is part of a distance expression, the gmllr:distanceAlong value is measured along the gmllr:LinearElement, beginning at the location specified by the gmllr:fromReferent in the direction towards the gmllrtr:towardsReferent. A gmllrtr:towardsReferent is only appropriate for Linear Referencing Method with towards referent, for example, the cross-street Linear Referencing Method.

9.4.4 DualAlongReferentPropertyType

complexType name=DualAlongReferentPropertyType sequence minOccurs=0 element ref=gmllrtr:DualAlongReferent sequence attributeGroup ref=gml:AssociationAttributeGroup complexType A property that has a dual along referent as its value domain may either be an appropriate dual along referent encapsulated in an element of this type or an XLink reference to a remote dual along referent where remote Copyright © 2012 Open Geospatial Consortium 45 includes dual along referents located elsewhere in the same document. Either the reference or the contained element shall be given, but neither both nor none.

9.5 Linear Referencing Offset